This invention relates to the art of reclosable bags, the material for making such bags, and is more particularly concerned with bags of the kind provided with extruded resiliently flexible plastic profiled reclosable separable fastener means.
The art of making reclosable bags equipped with extruded plastic profiled reclosable separable fastener means has seen a long period of developement as reflected in numerous patent disclosures. It has been conventional practice to extrude plastic material in tubular or strip sheet or web form with the profiled separable fastener means coextruded along and parallel to the longitudinal formation axis of the web, that is, the direction in which the web is extruded. On the other hand, prefabricated separable fastener strip means have been secured to separately formed web and with the fastener strip means extending longitudinally parallel to the longitudinal formation axis of the web.
By way of example, U.S. Pat. No. Re. 29,043 is referred to as disclosing coextrusion of web and fastener means and forming the same into bag sections.
U.S. Pat. No. 3,948,705 exemplifies the technique of securing reclosable separable fastener strips to plastic film parallel to the longitudinal formation axis of the web by fusion or heat seal methods.
Attachment of separable fastener strips parallel to the longitudinal formation axis of the web by adhesive means is exemplified in U.S. Pat. Nos. 4,372,793; 4,354,541; and 4,355,494.
U.S. Pat. No. 4,046,408 discloses separably interlockable fasteners along the edges of the plastic sheet material having generally arrow shaped profiles, the fasteners being either integrally extruded with flat sheets or tubes of plastic film, or supplied in the form of extruded strips attached to the web or film by heat sealing.
According to all of those prior patent disclosures, it is necessary to provide at least a pair of spaced longitudinally extending complementary profile fastener strips along the longitudinal extent of the bag material web or film so that when the material is folded upon itself along one or more folds parallel to the separable fastener strips, the fastener profiles will be aligned with one another in interlockable relation and extend along the top or bag mouth edges of the bag sections into which the material is subdivided by sealing the same at spaced intervals across the length of the material to provide closed sides for the bag sections.
Where separate matching strips of the web or film material carrying the complementary profile fastener strips longitudinally along the longitudinal extent of the material are aligned in face-to-face relation to provide bag sidewalls, the same requirements must be met as described for the foldable material for fabricating the same into bag sections, except that all side and bottom edges of the bag walls must also be secured together in those completed bags.
Those prior techniques do not necessarily limit the length of bags to be produced thereby, that is, the length from the bag top end to the bottom end of the bag, unless the bags are supplied for filling by the type of filling machines commonly referred to as form, fill and seal machines, such as exemplified in U.S. Pat. No. 4,355,494.
Where the fastener strip means are located longitudinally along the length of the bag making web material, the length of the bags that can be produced in the form, fill and seal machines is limited to the diameter of the filling nozzle about which the film or web material is progressively wrapped. Further, unless the fastener profiles are interlocked before the bag forming material is wrapped about the forming extent of the filling nozzle or at least before the usual longitudinal sealing of the joined longitudinal edges or margins of the bag forming material, there is a considerable problem with attaining interlockable registration of the fastener profiles.
Furthermore, if and when used on vertical form, fill, and seal apparatus, bag material as shown in U.S. Pat. No. 4,355,494 has certain shortcomings, as the material will produce finished bags having reclosable fastener means running in the longitudinal formation direction of the material and, thus, in a vertical direction along the bags. Such bags may not be commercially acceptable for some products, e.g., some types of candies, potato chips, and other snack foods.